title: Small angle X-ray scattering studies of mitochondrial glutaminase C reveal extended flexible regions, and link oligomeric state with enzyme activity.
abstract: Glutaminase C is a key metabolic enzyme, which is unregulated in many cancer systems and believed to play a central role in the Warburg effect, whereby cancer cells undergo changes to an altered metabolic profile. A long-standing hypothesis links enzymatic activity to the protein oligomeric state, hence the study of the solution behavior in general and the oligomer state in particular of glutaminase C is important for the understanding of the mechanism of protein activation and inhibition. In this report, this is extensively investigated in correlation to enzyme concentration or phosphate level, using a high-throughput microfluidic-mixing chip for the SAXS data collection, and we confirm that the oligomeric state correlates with activity. The in-depth solution behavior analysis further reveals the structural behavior of flexible regions of the protein in the dimeric, tetrameric and octameric state and investigates the C-terminal influence on the enzyme solution behavior. Our data enable SAXS-based rigid body modeling of the full-length tetramer states, thereby presenting the first ever experimentally derived structural model of mitochondrial glutaminase C including the N- and C-termini of the enzyme.
authors.affiliation: Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Magda
authors.initials: M
authors.lastname: Møller
authors.forename: Søren S
authors.initials: SS
authors.lastname: Nielsen
authors.forename: Sekar
authors.initials: S
authors.lastname: Ramachandran
authors.forename: Yunxing
authors.initials: Y
authors.lastname: Li
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Li
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Tria
authors.forename: Werner
authors.initials: W
authors.lastname: Streicher
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Petoukhov
authors.forename: Richard A
authors.initials: RA
authors.lastname: Cerione
authors.forename: Richard E
authors.initials: RE
authors.lastname: Gillilan
authors.forename: Bente
authors.initials: B
authors.lastname: Vestergaard
mesh_terms: D019540:Area Under Curve; D005972:Glutaminase / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D044085:Microfluidics; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009841:Oligonucleotides / Q000235:genetics; D011487:Protein Conformation; D053838:Scattering, Small Angle
chemical_list: D024101:Mitochondrial Proteins; D009841:Oligonucleotides; D005972:Glutaminase